The present invention relates to devices for injecting, delivering, infusing, dispensing or administering a substance, and to methods of making and using such devices. More particularly, it relates to infusion sets, an infusion set with a guiding needle, and an infusion set with a laterally displaceable guiding needle.
In patients that regularly require medication, the medication can be administered subcutaneously. For example, for certain groups of patients, e.g. those suffering from pain or patients with type I and type II diabetes, it can be useful to supply the body with a required quantity of medicament in liquid form via a cannula that is arranged in the subcutaneous tissue over quite a long period of time. For this purpose, an arrangement with a cannula made of an elastic material (soft cannula), and designated as an “infusion set” or “port”, depending on its design, is secured on the patient's skin in such a way that the cannula passes through the skin and into the subcutaneous tissue. To be able to insert the cannula through the skin into the subcutaneous tissue, it is supported by a guide needle which extends through the inside of the cannula channel and is then removed from the cannula in order to free the cannula channel for the delivery of medicament. Thereafter, the cannula is supplied with the required amount of liquid medicament, in the case of an infusion set by attaching a delivery catheter fed from a medicament-dosing device, or, in the case of a port, by a medicament reservoir that is to be filled at certain intervals by a syringe through a septum.
To avoid infections, the infusion set or the port has to be changed at regular intervals, for example every three days. In outpatient treatment, for example in the case of diabetics, this is often done by the patients themselves. It is therefore important that such infusion sets or ports are inexpensive and can be applied and removed easily and safely, and that their structural design allows operating errors to be ruled out as far as possible from the outset.
The prior art describes various infusion sets in which, after the cannula has been inserted into the tissue, the guide needle is manually removed from the infusion set in the axial direction via a grip part or by a spring-assisted retraction device. However, in such arrangements there is a possibility of the cannula being pulled completely or partially out of the puncture site. In addition, there is also a possibility that the user is injured by the unprotected guide needle.
The prior art also discloses infusion sets in which a flexible guide needle is pulled out of the infusion set via the medicament channel by various retraction devices, the guide needle being deflected through more than 90° by the boundary walls of the medicament channel and being further deformed in the retraction device. The retraction device, with the guide needle located in it, is then removed from the infusion set. Since the guide needle is received in the retraction device, these infusion sets do not pose any risk of injury to the operator. However, the deflection of the guide needle in the medicament channel poses a possibility of material being abraded from the boundary walls of the medicament channel, which may then be carried with the medicament into the subcutaneous tissue of the patient. Moreover, the production of practical designs according to this concept is difficult and expensive.
Therefore, there is a need in the medical device industry to make an infusion set wherein the guide needle can be safely removed from the cannula.